144 Mcfn-oi'andums, Hints, Precept s^ and Recipes, 



grand'is and a:rea, which devour everv thing, and are itl 

 their turn devoured bv the fwallows, which lind them in 

 fwarms. About the end of July or the bc>i;inning ot Auguft 

 the lecond brood appear, and accompanied with the like 

 circumftances." 



XXIII. Meviora7idums, Hints, Precepts, and Recipes^ for 



the Ufe of ylrlijis, MiwufaSlurrrs, and others; Including 

 'Ucirious Jhort Proccjjcs either neiu or little knoiun. 

 [To be occafionally continued.] 



On fame Kinds of Gilding. 



i TIE value which has alwavs been fet on articles made of 

 <rold, has induced artitts to devil'e means for giving to works 

 of other metals, by covering them with a thin iiratum of gold, 

 a crcatcr value than they really poflefs. Hence the origin of 

 gilding. 



In ^eal gilding, the metal is either immediately covered 

 with leaf gold, or an amalgam is formed of g«)ld and quick- 

 filvcr, with which the metal is rubbjd over, and the quick- 

 lilvcr is then iublimated by means of heat. 



In ffilding, a great deal depends on cleaning properly the 

 furface" of the metal to which the gilding is to be applied, 

 becaufe the union of the gold with the metal becomes then 

 more intimate. Silver, copper, brafs, and pinchbec, may 

 be eafily gilded, either by means of gold leaf, or of gold 

 amalcamalcd with mercury ; but iron and fteel with diffi- 

 culty; nor can fo durable a gilding be given to them as to 

 other metals bv any proccfles yet known. The caufe of this 

 is, that the furface of iron or ftecl during the procefs of gild- 

 ing cannot be kept^oroughly clean. 



Gilding Iron or Steel luiih Gold Leaf. 



In this procefs the metal muft be heated before the gold 

 leaf can be applied, which expofes it to the rifque of having 

 its furface oxidated, befides the danger of having the temper 

 at the fame time brought too low, when fword-blades, dag- 

 gers^ and the like, arc fubje6lcd to the procefs. 



Gilding lifith Amalgam and Nitrate of Mercury, 



In gilding iron or fteel by means of an amalgam, the diffi- 

 culty and the danger of mifcarrying are Itill greater; for, as 

 ihe metal has no affinity for the mercury, an agent muft be 

 employed to difpofe the furfiice to receive the gilding. For 



this 



